These investigations will focus on elucidating the mechanisms of messenger RNA degradation in prokaryotes and on identifying the structural features of bacterial transcripts that determine their stabilities. In particular, the decay of three mRNA species will be examined: the monocistronic ompA and bla messages of the enteric bacterium Escherichia coli and the polycistronic rxcA transcript of the photosynthetic bacterium Rhodopseudomonas capsulata. The experimental approach to be employed will involve creating defined mutations and fusions of these three genes in vitro, introducing these altered genetic constructs into appropriate bacterial hosts, and analyzing the decay of the resulting mRNA transcripts. The results of these studies should enhance our knowledge of a fundamental but much neglected aspect of gene expression that is poorly understood. This knowledge should ultimately be of value both to our understanding of a biological regulatory process that may be involved in human disease (e.g., Alzheimer's disease, thalassemia, cancer) and to efforts to improve yields of medically and commercially useful proteins produced in bacteria through recombinant DNA technology.